Fertilizers are conventionally formulated from active fertilizing ingredients and at least one filler. Fertilizers can be organic in nature, for example residue from sewage treatment plants, in which case the filler is usually organic, for example ground corn cobs, soybean oil meal or corn oil meal, or can be inorganic in nature and, in that instance, usually mixed with at least one inorganic filler. Inorganic fertilizers are usually blends of such materials as potassium chloride, diammonium phosphate, ammonium nitrate, super phosphates and urea in such proportions that they provide the relative amounts of nitrogen, phosphorus and potassium desired; the proportion of filler employed is that which gives the desired level of active fertilizer ingredients. Silica, limestone, dolomite and manufactured pellets have all been suggested as fillers for use with inorganic fertilizers. For example, U.S. Pat. No. 4,015,973, Perrine, suggests a method for producing the pellets from limestone, dolomite or marl and sodium bentonite, as well as compositions which are mixtures of fertilizers with the pellets. So far as is known, however, no previously suggested fertilizer composition has included a filler which materially reduces the tendency of the active fertilizer ingredients to cake with standing under more or less humid conditions.